1. Field of the Invention
The present invention relates to a crusher with a rotor for shearing (hereinafter referred to as "rotor shearing type crusher") which shearingly shreds of crushes municipal waste (such as carpets, cartridge gas cylinders, spray type cans), bulky waste (such as refrigerators, washing machines, television sets, bicycles, rear cars, furniture, beds), industrial waste (such as scrap tires, scrap plastic), construction waste (such as concrete, asphalt, timber, paper, sheet, string, rope), or for collection of useful resources from waste.
2. Description of Prior Art
It has been heretofore well known to introduce a preliminary process of shearingly crushing municipal waste and consecutively throwing the crushed waste in an incinerator before performing an incineration disposal of the municipal waste, for the purpose of improving incineration efficiency. In this process, a rotor shearing type crusher with dual shafts is popularly known as one functionally suitable apparatus and has been put into practical use. This rotor shearing type crusher mainly comprises a housing having a hopper-shaped charge port on the upper side and a discharge port for discharging crushed waste on the bottom side; and two rotary shafts disposed almost horizontally in the housing in such a manner as to be parallel to each other and rotatably supported. These two shafts are respectively provided with rotatable knives and spacer rings in an alternate manner so that the cutting edge of one rotary knife may move pass and nearby the outer periphery of a spacer ring of the other rotary knife to bite into the waste therebetween and otherwise shear the waste between side edges of the rotary knives.
Since there are obviously different types of municipal waste to be crushed in the crusher, various problems are apt to occur, being quite different from simple shredding of things of a fixed shape. To meet this situation, several attempts have been proposed to be added to the basic construction.
For example, in the apparatus disclosed in Japanese Laid-Open Utility Model Registrations Publication (unexamined) No. 63-51650 shown in FIG. 14, the rotatable knives 23a, 24a and the spacer ring 25a are alternately arranged on the rotary shafts 21a, 22a so that the rotatable knife of the one shaft may move pass and nearby the spacer ring of the other shaft and the rotation frequency of the two shafts is set to be different.
In the municipal waste, thin and soft vinyl bags, strings, underwear, socks, etc. are mixed and they are apt to twine themselves around the spacer ring without being crushed, resulting in a reduction in crushing performance. This disadvantage may be overcome to a certain extent by the mentioned difference in rotation frequency because the wastes are torn off between the rotatable knives and projections, then discharged.
Another attempt is disclosed in Japanese Utility Model Registration Publication (examined) No. 2-30030, as shown in FIG. 15, to solve a problem in which waste sticks to the periphery of the drum 102, wherein the drum 102 gradually makes the crushing gap smaller, finally closing the entire gap, thereby bringing about an overload problem. To overcome this problem, it is proposed by this publication to provide an actuator on the outside of the casing 1b so as to turn a scraper 104 and move it close to the periphery of the drum to scrape off the waste stuck to the drum.
However, there are so many kinds of waste thrown into an incinerator for disposal and accordingly there are also varieties of physical and chemical characteristics of such waste. Therefore, a variety of problems occur even with respect to a rotor shearing type crusher for carrying out pretreatment. In view of such a situation, it may be said that means of solving the previously mentioned problems are particularly needed which smoothly and exactly carry out the pretreatment of many kinds of waste materials with a single crusher.
Though it is a recent trend to conduct collection of classified waste with respect to domestic waste and those from factories, there is actually considerable differences in bulk or volume of each waste, and it may be required to enlarge a sectional area of the waste charge port of the crusher for throwing bulky waste therein. With such a crusher having a large waste charge port, however, another problem arises in that the thrown waste may not be concentrated on the center part between two rotatable knives but centrifugally dispersed to regions such as the side of corner portions of the apparatus where no shredding or crushing operation takes place, thus it becomes very difficult to effectively perform the necessary crushing of the waste. Particularly in case of cartridge gas cylinders, spray type cans and the like, it is essential to completely degas the inside thereof beforehand because there is a possibility of explosion of residual gas at the time of delivering them to the subsequent process of high speed hammer crushing or a further process of fluidized incineration. Moreover, this possibility of explosion is increased when the abrasion of rotatable knives proceeds to the extent of enlarging the gap between the rotatable knives and the spacer rings, because relatively small containers such as cartridge gas cylinders may pass through the gap without being crushed.
On the other hand, with the progress of abrasion, such waste as tires, carpets, vinyl products, plate, string, and rope which is flexible and deformable may be bitten or drawn in along the gap and, without being crushed, the bitten wastes may stick and twine themselves to and round the two rotatable knives resulting in an idle running problem.
Furthermore, there is a further possibility of some rigid material being mixed into other waste, the rigid material being absolutely unable to be crushed between the two rotatable knives. For example, waste such as used motors or steel ingots have high rigidity, and even if an attempt is made to forcibly crush this waste by biting it between the rotatable knives, without fail an overload will be applied to the crusher resulting in serious trouble for the crusher.
When some bulky waste such as refrigerators or washing machines are longitudinally thrown in a crusher, it is sometimes the case that the bottom side of such bulky waste mounts on the rotatable knives and takes a posture of being supported thereby, and as a result the rotatable knives are obliged to merely repeat idle running and is unable to bite into the bulky waste, thus the crushing operation makes no further progress.